Cabinets often employ interlocking mechanisms allowing only one drawer to be opened at a time. For example, U.S. Pat. Nos. 3,874,755 and 2,719,770 disclose filing cabinet locking mechanisms employing a single locking bar. Opening of one drawer causes the bar to be vertically displaced into a locking position by action of a member against an inclined surface. When the drawer is closed, a second inclined surface causes the bar to be returned to its original position. In both of these patents, socket and lug or ball mechanisms are used to maintain the rods in a raised position against gravity.